A suspension ring is known from US 2008/0315604 A1, in which the two parallel rectilinear legs are connected to one another by semicircular arcs as connecting legs. In this case, the chain strands adopt a position in this rounded portion of the connecting leg corresponding to the slope angle at the circumference of 0° to 60°. In this case, it is only with relative difficulty that the user can determine the slope angle in order to correctly estimate the load bearing capacity of a set of lifting tackle.
In the case of the suspension ring for multistrand lifting tackle of the kind shown in U.S. D661,862 S, the connecting legs are no longer of semicircular design but are provided with a larger rounding radius, thereby achieving better adaptation to the relatively flat crane hook and resulting in more extensive adaptation between the rounded portion of the connecting leg and the crane hook, thereby making it possible to reduce the wear on the hook and the ring. However, the difficulty of determining the slope angle and of estimating the load bearing capacity of a set of lifting tackle is not improved here.
In the case of multistrand lifting tackle, the load bearing capacity is specified as a function of the angle of the strands relative to an imaginary vertical or horizontal line or as a function of the angle which the strands enclose with one another. In the context of the present description, reference is in all cases to the angle which the strands enclose relative to an imaginary vertical line and which is referred to for short as the “slope angle”. Fundamentally, the load bearing capacity of a set of lifting tackle consists of the load bearing capacities of the individual chain strands as a function of the slope angle. Here, slope angles can be 0° to 60°. Slope angles greater than 60° are fundamentally not permitted. At the same time, it is relatively difficult for the user to determine the slope angle accurately or with some accuracy and hence to correctly estimate the load bearing capacity of a set of lifting tackle.
For general lifting operations, the standard angular range of 0° to 60° is divided into two ranges, which are assigned the lowest possible load bearing capacity of the respective range. Thus, for example, the angular range 0° to 45° is assigned the load bearing capacity of 45° and the angular range 45° to 60° is assigned the load bearing capacity of 60°. However, even with these subdivisions, it is not easy for the user to determine the slope angle range with a good degree of certainty.